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Press Release 94-21
Linda S. Ellis
(Bus: 216/433-2900)

High-Speed Engine Cycles Tapped for Further Research

Cleveland, OH -- A NASA-industry team has chosen two engine cycle concepts on which to focus the next 3 years of propulsion research for a next-generation supersonic airliner.

The "mixed flow turbofan" and "FLADE" (fan-on-blade) concepts were selected from six candidate engine cycles being considered in NASA's High-Speed Research Program, which is developing technology to make a future U.S. supersonic airliner environmentally compatible and economically practical.

"Both concepts promise to meet the economic and environmental goals for a new supersonic airliner," said NASA program Director Louis J. Williams. "Concentrating our propulsion research on these designs brings us one step closer to making this type of airplane a reality."

NASA Lewis Research Center leads the propulsion technology development for the agency's High-Speed Research Program.

NASA and industry selected the mixed flow turbofan and FLADE concepts because studies showed they were the best candidates in terms of direct operating costs to the airlines, noise reduction, adverse atmospheric effects and technological risk. Both concepts should reduce engine takeoff noise while maintaining good performance at supersonic speeds.

These engine cycles cut jet noise by mixing low-energy air with engine high-energy exhaust flows during takeoff. The mixed flow turbofan has a secondary, slower-moving airstream that bypasses most of the engine's turbomachinery but rejoins the airflow before reaching the engine exhaust nozzle. The FLADE is a modified turbofan engine that introduces an additional airstream up front in the engine fan.

NASA and industry will study these two concepts for the next 2 years before choosing one of them on which to focus technology development in the remaining years of the High-Speed Research Program. After that choice is made, large scale tests of the critical propulsion components -- inlet, fan, combustion chamber and nozzle -- would be done between 1998 and 2001, giving industry the data it needs for an informed decision to build a new supersonic airliner.

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